/**
 * 背景层
 */
require('node-easel');
var BGLayer = function(layer,width,height){
	this._layer = layer;
	this._width = width;
	this._height = height;
	this._bgImg = false;

	//白底
	this.whiteBg = new createjs.Shape();
	this.whiteBg.graphics.beginFill("#FFFFFF").drawRect(0,0,this._width,this._height);
	this._layer.addChild(this.whiteBg);

	/**
	 * 画画
	 * @param {Object} imageObj 要画的对象
	 */
	this.draw = function(imageObj){
		if(this._bgImg)
			this._layer.removeChild (this._bgImg);

		if(imageObj.isAdd != 0){
			this._bgImg = new createjs.Bitmap(imageObj.imageObj);
			this._bgImg.set({
				x:imageObj.x,
				y:imageObj.y,
				scaleX : imageObj.width/imageObj.imageObj.width,
				scaleY : imageObj.height/imageObj.imageObj.height
			});
			this._layer.addChild(this._bgImg);
		}
	}

	/**
	 * 清空
	 */
	this.clear = function(){
		this._layer.removeChild (this._bgImg);
	}

	/**
	 * 得到背景图
	 */
	this.getBg = function(){
		return this._bgImg;
	}

	/**
	 * 设置背景图
	 * @param {createjs.Bitmap} bitmap 要设置的bitmap
	 */
	this.setBg = function(bitmap){
		if(!bitmap)
			return;

		if(this._bgImg)
			this._layer.removeChild (this._bgImg);

		this._bgImg = bitmap.clone();
		this._layer.addChild(this._bgImg);
	}

};

module.exports =BGLayer;